Prunus rootstock named &#39;myrocot&#39;

ABSTRACT

A new and distinct  Prunus cerasifera×armeniaca  plant used as a rootstock for plum and apricot varieties that exhibits desirable propagation characteristics and white flowers.

BOTANICAL CLASSIFICATION

Prunus cerasifera×armeniaca

VARIETAL DENOMINATION

‘Myrocot’

BACKGROUND OF THE INVENTION

The present invention comprises a new and distinct cultivar of Prunus cerasifera×armeniaca used as a rootstock known by the varietal name ‘Myrocot’. The new variety was discovered in the Krasnodar region of Russia in 1997. The new variety is the result of planned breeding between Prunus cerasifera Seedling No. 3 (female parent, unpatented) and an unnamed Prunus armeniaca plant (male parent, unpatented). The new variety is similar to Prunus pumila×armeniaca ‘Druzba’ (unpatented) in leaf form and length, as well as fruit characteristics. ‘Myrocot’ has thinner one-year-old shoots than ‘Druzba’. The purpose of breeding ‘Myrocot’ was to provide adaptive, clonal rootstocks of semi-dwarf type vigor. The new variety has been trial and field tested and has been found to retain its distinctive characteristics and remain true to type through successive propagations. The following characteristics distinguish ‘Myrocot’ from other varieties known to the breeder:

-   1. The morphology is intermediate between myrobalan and apricot; -   2. High temperature and frost tolerance; -   3. Easy to propagate by cuttings; -   4. Plum compatible; -   5. Developed root system; and -   6. Resistant to root and leaf diseases.

Comparison information of ‘Myrocot’ to its parents is not available, as both parents no longer exist. However, Prunus cerasifera varieties are generally not compatible for use as a rootstock with apricot varieties, while ‘Myrocot’ is compatible with apricot varieties. Further, Prunus cerasifera varieties are generally more vigorous and larger than ‘Myrocot’. Additionally, Prunus armeniaca varieties are generally not compatible for use as a rootstock with plum varieties, while ‘Myrocot’ is compatible with plum varieties. Also, Prunus armeniaca varieties are more vigorous than ‘Myrocot’.

DESCRIPTION OF THE DRAWINGS

The accompanying photographic drawings illustrate the new variety, with the color being as nearly true as is possible with color illustrations of this type:

FIG. 1 shows the new variety grown to a flowering plant; and

FIG. 2 shows a close-up view of petals of the new variety.

The photographic drawings were taken of a 5 year-old ‘Myrocot’ plant in Oregon that is pruned to the ground yearly.

DETAILED BOTANICAL DESCRIPTION

The following detailed description sets forth the characteristics of the new cultivar. The data which defines these characteristics were collected by asexual reproductions via meristem inoculation, and cuttings carried out in the Krasnodar Region of Russia. The new variety was grown under standard apricot growing conditions outdoors in Russia. The color readings were taken in natural daylight, and the plant was 10 years old when described. Color references are primarily to the 1995 R.H.S. Colour Chart of The Royal Horticultural Society of London.

-   Tree: -   Size:     -   -   Height.—3.5 m.         -   Spread.—2.0 m. -   Vigor: Medium. -   Form: Rounded. -   Bearing: No fruit observed to date. -   Density: Medium. -   Pathogen resistance:     -   -   Fungal disease.—Stable.         -   Insects.—Susceptible to leaf insects.         -   Mites.—Tolerant.         -   Viruses.—Tolerant.         -   Other diseases.—Tolerant to bacterial disease. -   Rootstock performance:     -   -   Root sprouts (suckering).—None.         -   Anchorage.—Very well.         -   Compatibility.—Good with plum and apricot.         -   Vigor.—Medium. -   Trunk:     -   -   Size.—16 cm. at approximately 25 cm. from the ground.         -   Bark color.—200C.         -   Surface texture.—Smooth.         -   Lenticels.—Length: 2.5 cm. Color: 198B. Density: High. -   Branches:     -   -   Diameter.—0.4 cm.         -   Surface texture.—Smooth, no pubescence present.         -   Color.—177B.         -   Average angle.—26°.         -   Lenticels.—Length: 1.5 cm. Width: 0.5 cm. Density: Dense.             Color: 200A. Shape: Small and rounded early in growth; on             older bark, the lenticels are elongated and numerous. -   Leaves:     -   -   Length.—4.8 cm.         -   Width.—3.7 cm.         -   Form.—Oval.         -   Base.—Acute.         -   Apex.—Obtuse/acute.         -   Margin.—Serrate.         -   Pubescence.—Upper surface: Almost absent. Lower surface:             Little present.         -   Color.—Young leaves: Upper surface: 211C. Lower surface:             198A. Mature leaves: Upper surface: 198A. Lower surface:             189C.         -   Petiole.—Length: 3 cm. Color: 135B. Surface texture: Smooth.         -   Veins.—Venation type: Medium. Color: Upper surface: 211C.             Lower surface: 135C. -   Flower buds:     -   -   First bud burst.—Approximately mid-April in Oregon, but             varies by region.         -   Pedicel.—Length: 2.5 cm. Diameter: 1 cm. Color: 144B.         -   Bud.—Length: 2 cm. Width: 3.5 cm. Color: 200A. -   Flowers:     -   -   Blooming period.—April 5-April 15 in the Krasnodar region of             Russia.         -   Pollination requirements.—Autofertile.         -   Number of flowers per raceme.—3.         -   Fragrance.—Weak.         -   Petals.—Number: 5. Length: 4.5 cm. Width: 3.7 cm. Shape:             Cupped. Aspect: Flat. Margin: Entire.         -   Color.—When opening: Upper surface: 155C. Lower surface:             155C. Fully opened: Upper surface: 155C. Lower surface:             144D.         -   Sepals.—Shape: Oval. Margin: Entire. Length: 3.5 mm. Width:             3.5 mm.         -   Color.—Upper surface: 201C. Lower surface: 201C.         -   Stamens.—Number (per flower): 12.         -   Anthers.—Shape: Rounded. Length: 1 mm. Color: 22A.         -   Pollen.—Color: 9A. Amount (generally): Plentiful.         -   Pistils.—Average number: 5. Length: 1.8 mm.         -   Style.—Length: Medium. Color: 9A.         -   Stigma.—Shape: Reniform. Color: 9A. -   Fruit:     -   -   Size.—Diameter: Small; 3.5 to 4.0 cm. Length: 3.5 cm.         -   Skin.—Thickness: Fine. Texture: Soft. Tendency to crack:             Strong. Color: 201C. Ground color: 21A.         -   Flesh.—Aroma: Weak. Color: 21A. Texture: Soft. Eating             quality: Fair.         -   Seeds.—Number per fruit: 1. Length: 1.6 cm. Breadth: 1.2 cm.             Form: Oval. Color: 164B.         -   Stem.—Length: 1.5-2.0 cm. Width: 2 mm. Color: 136C. -   Tree winter hardiness: USDA Hardiness Zone 4. -   Bud winter hardiness: USDA Hardiness Zone 4. -   Drought tolerance: High. -   Insect resistance: Nematode resistance. -   Disease resistance: No particular disease resistance observed to     date. -   Multiplication ability: The new variety may be multiplied by     hardwood cuttings, softwood cuttings, and micropropagation (tissue     culture). -   Soil adaptation and tolerance: Moderate tolerance to chlorosis and     adapts to most soil types (light to heavy soils). -   Yield efficiency: Above average yield efficiency for both apricot     and plum scions. 

1. A new and distinct variety of Prunus cerasifera×armeniaca plant, as herein illustrated and described. 